1. Technical Field of the Invention
The invention relates to a power transmission chain, each link of which displays two side walls and a stabilising element joining these at their longitudinal edges, as well as a cover which connects the two side walls and can be snapped onto one and/or both pairs of longitudinal edges. The consecutive links are joined in pivoting fashion, the covers can be fixed on the corresponding longitudinal edges of the side walls in a detachable fashion, and the covers of consecutive links can be connected together.
2. Prior Art
A power transmission chain of this kind is known, for example, from DE-PS 3930291. The power transmission chain described there consists of links comprising two side walls, a cross-member connecting these, and a snap-on cover. The covers of the power transmission chain are provided with claws, the upper edges of the side walls with snap-in cut-outs for detachable accommodation of the claws, and the covers are joined in pivoting fashion by round bars and slots to accommodate them. Slits are provided which permit engagement of the round bars into the slits and withdrawal therefrom. One particular advantage of power transmission chains of this kind is that the covers can be detached or torn off in a continuous strip.
The use of such power transmission chains, which have proven successful in numerous practical applications, is also conceivable and desirable in computers, business machines, measuring instruments or other electrical equipment in which very small cables or wires are used.
One disadvantage of the power transmission chain known from DE-PS 3930291 is the fact that there are limits on the smallest size in which it can be manufactured. On the one hand, important parts, such as the round bar described in DE-PS 3930291, lose the strength necessary for removing the covers and, on the other hand, there is a disproportionately great reduction of the space available for these parts. This means that the overall height available for the cover connecting elements is reduced to such an extent that these can no longer be manufactured with sufficient strength. Furthermore, the connecting elements (round bars and slotted slits) also become more difficult to handle. A reduction of the inside dimensions of the power transmission chain, in order to create the desired design space, is undesirable, as the ratio of the inside dimensions to the outside dimensions of the power transmission chain sealed with covers should preferably be identical in all sizes of power transmission chain.
Furthermore, in the power transmission chain designed according to the principle described above, when the chain links are deflected at large angles relative to each other, very high frictional forces occur in the area where said round bar comes into contact with the upper or lower wall of the slot, depending on the direction in which the chain links are deflected. These frictional forces have virtually no effect in the case of large links. However, if the scale of the links were to be greatly reduced, the frictional forces would severely impair the running properties of the power transmission chain. Consequently, it would not be possible to select a very small value for the rolling radius, i.e. the distance between upper strand and lower strand when deflecting the chain.